Generally, corrugated paperboard boxes include a peripheral wall formed by bending the corrugated paperboard into a tubular shape, and a plurality of flaps integrally connected to one end of the peripheral wall, and are formed with a normal scoreline at the boundary area between the flaps and the peripheral wall so that the flaps can be smoothly bent along the normal scoreline toward the inner surface of the peripheral wall. The corrugated paperboard, of which such a corrugated paperboard box is made, includes an outer linerboard, an inner linerboard, and a corrugated medium provided between the outer linerboard and the inner linerboard. The normal scoreline at the boundary area between the flaps and the peripheral wall is recessed on the side of the inner linerboard (i.e., on the inner side of the box).
When products are packed in such a corrugated paperboard box, in order to enable the products to be easily placed into the box, the flaps are bent toward the outer surface of the peripheral wall (i.e., bent outwardly) in some cases. Since the normal scoreline at the boundary area between the flaps and the peripheral wall is a groove-shaped scoreline recessed on the side of the inner linerboard, the flaps can be smoothly bent inwardly along the normal scoreline. However, the flaps are less likely to be bent outwardly. Therefore, when products are packed in such a corrugated paperboard box, it is necessary to hold the flaps by hand with the flaps bent outwardly such that the flaps do not elastically return.
In order to overcome such a problem, Japanese Unexamined Utility Model Application Publication No. S60-123317 proposes a corrugated paperboard box including a flap 201 and a peripheral wall 202, and formed, as illustrated in FIG. 57, at the boundary area between the flap 201 and the peripheral wall 202 with a normal scoreline 203 along which the flap 201 can be bent toward the inner surface of the peripheral wall 202, and a reverse scoreline 204 along which the flap 201 can be bent toward the outer surface of the peripheral wall 202.
In order to make it possible to easily open the corrugated paperboard box formed at the boundary area between the flap 201 and the peripheral wall 202 with the normal scoreline 203, along which the flap 201 can be bent toward the inner surface of the peripheral wall 202, and the reverse scoreline 204, along which the flap 201 can be bent toward the outer surface of the peripheral wall 202, as illustrated by the dashed line in FIG. 57, the inventors of the present application considered forming, at the position of the normal scoreline 203 of the corrugated paperboard box, a perforated line 205 along which the flap 201 can be separated from the peripheral wall 202.
If the perforated line 205 is formed at the position of the normal scoreline 203, it is possible to easily open the corrugated paperboard box by separating the flap 201 along the perforated line 205 from the peripheral wall 202 with the box closed by the flap 201. Also, after separating the flap 201 along the perforated line 205 from the peripheral wall 202, it is possible to display products at a storefront with the products received in the corrugated paperboard box, namely, without taking the products out of the box.
However, when the inventors of the present application experimentally prepared in their company a corrugated paperboard box which is formed at the boundary area between the flap 201 and the peripheral wall 202 with the normal scoreline 203, along which the flap 201 can be bent toward the inner surface of the peripheral wall 202, and the reverse scoreline 204, along which the flap 201 can be bent toward the outer surface of the peripheral wall 202, and wall 202, and which is further formed at the position of the normal scoreline 203 with the perforated line 205, along witch the flap 201 can be separated from the peripheral wall 202, it turned out that when the flap 201 is bent along the normal scoreline 203 toward the inner surface of the peripheral wall 202, the perforated line 205 tends to break.
Therefore, the inventors of the present application investigated what causes the perforated line 205 to break when bending the flap 201 along the normal scoreline 203 in the above corrugated paperboard box, experimentally prepared in their company, and noticed the following point.
When the boundary area between the flap 201 and the peripheral wall 202 is sandwiched from the side of an outer linerboard 206 and the side of an inner linerboard 207, the normal scoreline 203 is formed. Similarly, when the boundary area between the flap 201 and the peripheral wall 202 is sandwiched from the side of the outer linerboard 206 and the side of the inner linerboard 207, the reverse scoreline 204 is formed. Namely, if both the normal scoreline 203 and the reverse scoreline 204 are formed, the boundary area between the flap 201 and the peripheral wall 202 is sandwiched twice, specifically, when the normal scoreline 203 is formed, and when the reverse scoreline 204 is formed, thereby receiving a large tensile load. This decreases, to a large degree, the tensile strengths of the portions of the linerboards 206 and 207 located at the boundary area between the flap 202 and the peripheral wall 202.
Therefore, it turned out that if both the normal scoreline 203 and the reverse scoreline 204 are formed, and further the perforated line 205 is formed at the position of the normal scoreline 203, the perforated line 205 tends to break. Namely, when the flap 201 is bent along the normal scoreline 203 toward the inner surface of the peripheral wall 202, the perforated line 205 tends to break due to the tension applied to the outer linerboard 206.
In order to make it possible to easily open the corrugated paperboard box, as illustrated in FIG. 36(A), the inventors of the present application considered forming, on a normal scoreline 208 along which the flap can be bent and which are recessed on the side of an inner linerboard 2, a perforated line 17 along which the flap can be separated. With this arrangement, it is possible to easily separate the flap along the perforated line 17, located within the normal scoreline 208, namely, to easily open the corrugated paperboard box.
However, when the inventors of the present application experimentally prepared a plurality of corrugated paperboard boxes in which the perforated line 17 is formed within the normal scoreline 208, along which the flap can be bent, and evaluated these boxes, it turned out that when the flap is bent along the normal scoreline 208 toward an outer linerboard 1 (i.e., bent in the reverse direction), the perforated line 17 tends to break.
Thereafter, when the inventors of the present application experimentally prepared a corrugated paperboard box so as to consider why the perforated line 17 tends to break, instead of forming the normal scoreline 208, recessed on the side of the inner linerboard 2 (i.e., on the inner side of the box) as illustrated in FIG. 36(A), they tried forming a reverse scoreline 16 recessed on the side of the outer linerboard 1 (i.e., on the outer side of the box) as illustrated in FIG. 36(B).
As illustrated in FIG. 36(B), this experimentally prepared corrugated paperboard box is formed at the boundary area between the flap and the peripheral wall with a groove-shaped reverse scoreline 16 recessed on the side of the outer linerboard 1, and a perforated line 17 located within the reverse scoreline 16, and comprising a plurality of cuts formed by cutting the box from the side of the inner linerboard 2 toward the side of the outer linerboard 1 with a perforation forming knife 89.
After bending the flap of this corrugated paperboard box along the perforated line 17, the inventors noticed that the perforated line 17 does not break both when the flap is bent along the perforated line 17 toward the outer linerboard 1, and when the flap is bent along the perforated line 17 toward the inner linerboard 2.
Moreover, the inventors considered why the perforated line 17 does not break in the above corrugated paperboard box, experimentally prepared in their company, and noticed the following point: If, as illustrated in FIG. 36(A), the normal scoreline 208, recessed on the side of the inner linerboard 2, and the perforated line 17, cut from the side of the inner linerboard 2, are formed in the box such that the perforated line 17 is located within the normal scoreline 208, when the normal scoreline 208 is formed, the inner linerboard 2 is pulled and receives a large load, and when the perforated line 17 is formed too, the inner linerboard 2 receives a larger load than the load which the outer linerboard 1 receives. Namely, loads concentrate on the inner linerboard 2, so that the perforated line 17 tends to break very easily on the side of the inner linerboard 2. In contrast thereto, if, as illustrated in FIG. 36(B), the reverse scoreline 16, recessed on the side of the outer linerboard 1, and the perforated line 17, cut from the side of the inner linerboard 2, are formed in the box such that the perforated line 17 is located within the reverse scoreline 16, when the reverse scoreline 16 is formed, the outer linerboard 1 receives a large load, and when the perforated line 17 is formed, the inner linerboard 2 on the opposite side of the outer linerboard 1 receives a large load. Namely, loads do not concentrate on one of the outer and inner linerboards 1 and 2, so that the perforated line 17 is relatively less likely to break.
When the inventors of the present application experimentally prepared a plurality of corrugated paperboard boxes in which the perforated line is formed within the normal scoreline between the flap and the peripheral wall, and evaluated these boxes, it turned out that when products are packed in the boxes, the boundary area between the flap and the peripheral wall might break along the perforated line.
Namely, when products are packed in such a corrugated paperboard box, in order to enable the products to be easily placed into the box, the flaps are bent toward the outer surface of the peripheral wall (i.e., bent in the reverse direction) in some cases. Since the normal scoreline between the flap and the peripheral wall is a groove-shaped scoreline recessed on the side of the inner linerboard, when the flap is bent toward the inner surface of the peripheral wall, the flap can be bent naturally and accurately along the normal scoreline. However, a relatively large force is required to bend the flap toward the outer surface of the peripheral wall, namely, when the flap is bent outwardly, a large tension is applied to the inner linerboard. If the perforated line is formed within the normal scoreline between the flap and the peripheral wall, when the flap is bent along the normal scoreline toward the outer surface of the peripheral wall, the boundary area between the flap and the peripheral wall might break along the perforated line due to the tension applied to the inner linerboard.
It is an object of the present invention to provide a corrugated paperboard box in which when a flap is bent, a perforated line along which the flap can be separated from the box is less likely to break.